Soviet Union

The Union of Soviet Socialist Republics (Russian: Сою́з Сове́тских Социалисти́ческих Респу́блик, tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik; IPA: [sɐˈjus sɐˈvʲɛtskʲɪx sətsɨəlʲɪsˈtʲitɕɪskʲɪx rʲɪˈspublʲɪk]) abbreviated to USSR (Russian: СССР, tr. SSSR) or shortened to the Soviet Union (Russian: Сове́тский Сою́з, tr. Sovetskij Soyuz; IPA: [sɐ'vʲetskʲɪj sɐˈjʉs]), was a Marxist–Leninist state on the Eurasian continent that existed between 1922 and 1991. A union of multiple subnational Soviet republics, its government and economy were highly centralized. The Soviet Union was a one-party state, governed by the Communist Party with Moscow as its capital.

Red Army

The Workers' and Peasants' Red Army (Russian: Рабоче-крестьянская Красная армия; РККА, or Raboche-krest'yanskaya Krasnaya armiya: RKKA, frequently shortened in Russian to Красная aрмия; KA, in English: Red Army) was the army and the air force of the Russian Soviet Federative Socialist Republic, and after 1922 the Union of Soviet Socialist Republics. The army was established immediately after the 1917 October Revolution (Red October or Bolshevik Revolution). The Bolsheviks raised an army to oppose the military confederations (especially the various groups collectively known as the White Army) of their adversaries during the Russian Civil War. Beginning in February 1946, the Red Army, along with the Soviet Navy, embodied the main component of the Soviet Armed Forces; taking the official name of "Soviet Army" (Russian: Советская Армия (СА)/Sovetskaya Armija), until its dissolution in December 1991.

The Red Army is credited as being the decisive land force in the Allied victory in the European theatre of World War II. During operations on the Eastern Front, it fought 75%–80% of the German land forces (Wehrmacht and Waffen-SS) deployed in the war.

Soviet–Afghan War

The Soviet–Afghan War lasted over nine years from December 1979 to February 1989. Insurgent groups ("the Mujahideen") who received aid from both Christian and Muslim countries, fought against the Soviet Army and allied Afghan forces. Between 850,000–1.5 million civilians were killed and millions of Afghans fled the country as refugees, mostly to Pakistan and Iran.

Prior to the arrival of Soviet troops, the pro-Soviet Nur Mohammad Taraki government took power in a 1978 coup and initiated a series of radical modernization reforms throughout the country. Vigorously suppressing any opposition from among the traditional Muslim Afghans, the government arrested thousands and executed as many as 27,000 political prisoners. By April 1979 large parts of the country were in open rebellion and by December the government had lost control of territory outside of the cities. In response to Afghan government requests, the Soviet government under leader Leonid Brezhnev first sent covert troops to advise and support the Afghani government, but on December 24, 1979, began the first deployment of the 40th Army. Arriving in the capital Kabul, they staged a coup, killing the Afghan President, and installing a rival Afghan socialist (Babrak Karmal).